The natural history of early recovery from myocardial infarction will be evaluated by three test methods: treadmill exercise testing, work simulation, and psychological "Stress testing". Objectives include definition of: 1) prognosis (incidence of ventricular ectopic activity and myocardial ischemia), 2) functional capacity, and 3) the cardiovascular responses to psychologically stressful stimuli (heart rate, blood pressure, ventricular ectopic activity, myocardial ischemia). This evaluation, applied prospectively to patients being considered for return to work, will provide the basis for evaluating the success of functional as opposed to clinical evaluation in the return of patients to work following myocardial infarction. Objective determination of cardiovascular response to on-the-job conditions will be used to evaluate the predictive value of the laboratory "work evaluation". The effects of individualized, graded physical activity in the early (7-21 days) and later (3-11 weeks) on functional capacity, will be evaluated, as well as the effectiveness of home vs. supervised gymnasium programs of physical activity. The extent to which long-term medical, occupational, psychological, and sociological outcomes can be predicted by early evaluation will be determined. BIBLIOGRAPHIC REFERENCES: Fitzgerald, J.W., Houston, N., and DeBusk, R.F.: Natural history of ventricular arrhythmia in postinfarction patients. Circulation (Suppl II to vols 53 and 54): II-10, 1976. Presented at the 49th Scientific Session of the American Heart Association, Miami Beach, November 15-18, 1976. Gradman, A.H., Bell, P.A., and DeBusk, R.F.: Sudden death during ambulatory monitoring. Clinical and electrocardiographic correlations. Report of a case. Circulation 55: 210-211, 1977.